Couplers are known for securing construction attachments, such as buckets, impact hammers, shears, etc., fixedly and operatively to both an arm (or “dipper-stick”) and a control link of a tractor, backhoe, excavator or other type of construction/agricultural machine (the term “excavator” as used herein is intended to encompass an excavator, tractor, backhoe, and/or other machine having an arm and a control link). As is generally well known, these couplers are used as an alternative to a pin-on connection for operatively securing an associated attachment to the arm and control link. The control link is used to pivot the coupler (and any attachment coupled thereto) relative to the arm to adjust the angular position or orientation of the coupler relative to arm. The coupler includes a lock system for releasably engaging and retaining first and second parallel attachment pins that are secured to the attachment.